Thesis
Effects of drought and rhizobia abundance on tri-trophic interactions mediated by a vector-borne pathogen in a legume host
Washington State University
Master of Science (MS), Washington State University
05/2021
DOI:
https://doi.org/10.7273/000004268
Handle:
https://hdl.handle.net/2376/124916
Abstract
In the Palouse region of eastern Washington and northern Idaho, a vector herbivore (pea aphid, Acyrthosiphon pisum) and a vector-borne pathogen (Pea enation mosaic virus, PEMV) co-occur both in wild and cultivated legumes and cause huge economic loss. Legume fields of Palouse also harbor soil growth promoting rhizobia which are well known in promoting legume growth and resilience against herbivores and pathogens. Besides all the biotic stressors, plants in agroecosystems are exposed regularly to various abiotic stressors including drought. However, few studies have investigated the effects of soil rhizobia and multiple stressors on legume hosts. In my dissertation work, I studied effects of drought and rhizobia on intricate and complex interactions mediated by host plant (Pisum sativum), a vector herbivore (pea aphid, A. pisum) and a plant virus (PEMV). In the first Chapter, I assessed if soil rhizobia mediated interactions among Pisum sativum, A. pisum and PEMV under a drought condition by measuring plant height, node count, osmotic pressure, virus prevalence and defense gene expressions. I found beneficial effects of soil microbes on plant health can be mediated by biotic stressors and variation in abiotic conditions. Understanding the conditions where plant mutualistic bacteria like rhizobia are likely to protect plants would improve our ability to prevent outbreaks of devastating herbivores and pathogens. In the second chapter, I examined the effects of abundance of soil rhizobia on tri-trophic interactions mediated by a vector-borne pathogen in pea by measuring plant growth, nodule count, virus prevalence and expression of various defense genes related to phytohormone signaling. My results indicate that, using appropriate concentrations of compatible soil rhizobia inoculum, may contribute to effective, superior mutualism and novel management tactic to manage devastating herbivores and plant pathogens they transmit while improving crop yield and nitrogen fixation. Overall, better pathogen management following mutualisms between legume and rhizobia under harsh environmental conditions could promote tolerance to pathogens and herbivores.
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Details
- Title
- Effects of drought and rhizobia abundance on tri-trophic interactions mediated by a vector-borne pathogen in a legume host
- Creators
- Pooja Malhotra
- Contributors
- David William Crowder (Advisor) - Washington State University, Entomology, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Entomology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900896414501842
- Language
- English
- Resource Type
- Thesis